Fluorination of fiber form polyesters has been discovered to impart desirable properties to the final fabric, certainly from the viewpoint of wearing apparel. The soil resistance and moisture transport properties are greatly improved. Reference is made to copending application Ser. No. 434,285, filed Jan. 17, 1974 for detailed explanation of the fluorination procedure, and the resulting properties of the polyester.
Of significance, both apparel purposes and for tire reinforcement purposes, is that fluorination creates carboxylate groups on the surface of the polyester material. (The carboxylate groups are believed to be the reason for considerable improvement in moisture transport.) Within the context of employing polyester yarns, tire cord and fabric for tire reinforcement purposes, the carboxylate groups are polar reactive groups important for good adhesion in a laminate. Indeed one explanation offered for the relatively poor adhesion of polyester tire cord has been the absence of potentially reactive groups in the polyester macromolecule. In theory at least, the isocyanate dip involves chemical reactions which add reactive groups to the polyester surface.
Presence of carboxylate groups in the rubber formulation has been contemplated, e.g. by inclusion of acrylate moieties within the rubber formulation polymers. The test results indicated that adhesion of rubber to fibrous reinforcement that was in fact improved. However, carboxylate containing rubber formulations have not been adopted by the industry.